Semiconductor Laser Groove Formation for Optical Performance
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Solution Overview
Problem
The formation of cleavage guide grooves in semiconductor laser elements using AlGaInN-based group-III nitride semiconductors often results in microscopic irregularities, leading to line-shaped step differences that reduce optical output power and deteriorate Far Field Pattern (FFP) due to scattering of light, as existing techniques like RIE and laser processing are inefficient and introduce surface irregularities.
Innovation Solution
A method involving the formation of first grooves spaced apart from optical waveguides and second grooves with smoother surfaces, intersecting the extended direction of the first grooves, to prevent line-shaped step differences from reaching the optical waveguides during cleavage, thereby enhancing optical output power and FFP characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cleavage guide grooves are formed using RIE (Reactive Ion Etching), then the dividing direction can be controlled, but the processing time increases which decreases productivity
Solution Approach 1:
The patent replaces the mechanical/chemical RIE etching process with a laser beam processing method. The laser beam forms cleavage guide grooves by melting and evaporating material, substituting the complex plasma chemistry of RIE with direct optical energy conversion to thermal energy, thereby reducing processing time while maintaining dividing direction control
Solution Approach 2:
The patent changes the processing parameters by using laser beam conditions (wavelength, power, scanning speed) that enable rapid material removal. By adjusting these parameters, the grooves can be formed quickly while controlling their geometry to ensure proper cleavage direction
2Productivity
If cleavage guide grooves are formed using laser beam processing, then productivity increases, but microscopic irregularities occur on the groove surfaces which reduce optical output power and deteriorate FFP
Solution Approach 1:
The patent introduces a protective film as an intermediary layer between the laser beam and the semiconductor wafer. This film absorbs the laser energy and transfers it to the wafer in a controlled manner, preventing direct laser-material interaction that causes surface irregularities. The protective film is removed after groove formation, leaving smooth groove surfaces
Solution Approach 2:
The patent applies a protective film to the wafer surface before laser processing. This preliminary action prepares the surface to receive laser energy in a controlled way, preventing the formation of microscopic irregularities during the grooving process. The film is subsequently removed to reveal the smooth grooves
3Productivity
If high energy laser processing is used to form grooves quickly, then productivity improves, but line-shaped step differences are generated that scatter light and reduce optical performance
Solution Approach 1:
The protective film serves as a mediator that converts the high-energy laser processing into a controlled thermal process. The film absorbs and distributes the laser energy uniformly, preventing the formation of step differences while still enabling rapid groove formation. Without the film, direct high-energy laser processing would create the harmful step differences
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively blocks line-shaped step differences and prevents their formation, resulting in semiconductor laser elements with improved optical output power and FFP, increasing productivity and reducing the adverse effects on optical performance.
Implementation Method 1
a processing technique using a laser beam
Implementation Method 2
since the formation is conducted using a high energy for a short time
Implementation Method 3
forming a plurality of first grooves on at least one of an upper surface and a lower surface of the wafer
Data Source
AI summary
A method of manufacturing a semiconductor laser element including: preparing a wafer; forming first grooves on at least one of an upper surface and a lower surface of the wafer, each of the first grooves being spaced apart from the optical waveguide formed in the wafer and extending in a direction intersecting the optical waveguide in a plan view; forming second grooves on the one of the upper surface and the lower surface of the wafer, each of the second grooves extending in a direction intersecting a straight line extended from each of the first grooves, and each of the second grooves having a smooth surface compared with the first grooves; dividing the wafer along the first grooves to obtain a plurality of laser bars; and dividing the laser bars in a direction intersecting an extending direction of the first grooves to obtain the semiconductor laser elements.